Long Term Objectives: Since magnetic resonance (MR) imaging, x-ray computerized tomography (CT), and positron emission tomography (PET) provide complementary information about brain anatomy and function, a given patient often undergoes more than one of these procedures. The physician is then presented with a large number (e.g. 100) of cross-sectional images which may have different geometrical orientations and which portray different aspects of brain anatomy and function. He must integrate this huge amount of fragmented information into a coherent mental picture of the brain. The long term objective of this proposal is to develop software for displaying this information in an explicitly integrated fashion. Specifically, spatial integration will be achieved by using computer graphics to create 3-D renditions of brain anatomy or function from each modality. Multimodality integration will be accomplished by fusing these separate 3-D views into a single, comprehensive model of the brain. Interactive software will be developed for exploring and manipulating this 3-D model, so that anatomical and functional information can be examined at any point and from any viewing angle. This software is expected to be useful for medical diagnosis, surgical planning, radiation therapy planning, and medical education. Specific Aims: Preliminary work in the applicant's laboratory has demonstrated the feasibility of achieving the following aims: 1. Techniques will be developed for using MR images to create 3-D renditions of the surface of the brain, surface of the skin, selected internal structures (e.g. lesions), and blood vessels. The accuracy of each type of rendition will be measured experimentally. 2. PET data will be used to create 3-D views of metabolic activity in the brain's cortex. An existing technique for retrospective image registration will be used to fuse the data from MR and PET into a single integrated 3-D model of brain anatomy and function. Clinical tests of the accuracy of the combined display will be performed. 3. Software "switches" will be developed so that the user can view any combination of anatomical features from MR and functional data from PET. Other tools will enable the operator to "roam through" the 3-D model and inspect cross-sectional images at any selected point. Software for surgery simulation will be written so that the user can "rehearse" surgical procedures on the 3-D model.